PCECD_seek
The PC Engine is a video game machine which was released in 1987 in Japan, with a CDROM attachment released prior to 1990, before many of the CDROM standards we know today were created.
This CDROM was 1x speed, and a full-disc seek took over 1 second to execute. Many of the games were written to take this timing into account, and either wait for an interval, or even exeute some work during that period. If the operation were to complete more quickly - as it does on nearly all modern emulation - that interim work would be incomplete when the operation finishes.
In either scenario, the user is left with a substandard experience.
This project details a collection of measurements and tools I used to check the actual time required for CDROM seeks on original (but re-capped) hardware.
Notes:
measurements/* :
- A series of statistics measured empirically, of varying degress of seek distance, from different offsets on disc. Unless otherwise noted, these are measured in VSYNC interrupts signals, which occur at 60 Hertz (almost exactly). The measurements were performed at this resolution because it was available directly on the machine, and provides an adequate level of resolution for times of thiese durations.
seektest2_huc/*:
- This is a testing program, written with HuC v3.21 and running on the CD System Card, which was used for taking measurements
- It uses relatively large but sparse files to space out the CD image so that a large seek can be performed on the media. Both the fixed-size bulk data and the final ISO file are stored in ZIP format in order to conserve space and bandwidth
seekaud_huc/*:
- This is a newer addition to the test set, which measures the difference between the time taken to seek to a location on an audio track (and confirm back to the calling function), and the actual playback of the sound at that point.
- This does not need any specialized test equipmnet, but it will require: a) Connection back to a computer for capture of audio output b) Audacity or some other audio editing program to view the actual waveform c) A large audio file with no gaps (for example, generated by Audacity).
seektime.c :
- A 'C' program to calculate effective seektime based on start and end sectors.
- Originally written for Linux
Use this information and software at your own risk.